E:, or any. There are no drive letters at all. What now? How will you know where is what? Easy, you don’t need silly letters at all, never mind what windows and other apertures keep telling ya!
When you partition a drive (represented by a letter a-z), you will assign a number to identify your partition. The first hard drive, for example, will be called
sda (HDDs are usually prefixed with “sd”). The first partition on the first hard drive will then be called
sda1, the second one
sda2, and so on. If you have a second HDD, it will most likely be called
sdb, with partitions such as
sdb2, etc. You can also assign labels to these partitions, so that some file system browsers can identify the drives by labels, rather than numbers and letters, making it human readable.
If you have for example three partitions,
sda3, the first containing your Linux system, the second your
home directory (more on that later), and the third one is an extra data storage, you can label them the following way:
When you use a graphical tool, like a file system browser, it will be able to identify your partitions by the labels, rather than the number/letter combination, making it somewhat similar to calling them drive
E:. Why not use drive letters then? Well, for one, these are Window$-specific, and even if they were not, this method offers more flexibility. You can call your drives whatever you want, you are not bound by single letter names starting with “C”, which, however much you might be used to it, makes little practical sense. (Yes you can assign labels in Windows too, but your drives will be still referenced by drive letters.)
So far the difference is only the nomenclature, but for advanced users, there is a lot more possibility. Your Windows installation will usually be on one drive (most possibly
C:), in a few pre-defined system folders. In Linux, you can assign various system components to different partitions. System root can be one partition, the home directory (all the user data) on another, you can have a separate partition for
/tmp (temporary files), for
/boot (yes, it handles system boot), and others too. You have greater control over the make-up of your system, or you can just choose to put everything in one place like Windows does.
For beginners, and average home users, it makes sense to create at least three partitions: One for the system, one for
swap (virtual memory) and one for the
/home directory. This will make your swap file reusable, and separates your data from your system, meaning, if you update/upgrade your system, or even reinstall it, your data will still be there.